Question

/*Contents of CalendarProgran.class */

//Import packages
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class Calendar{
    static JLabel lblMonth, lblYear;
    static JButton btnPrev, btnNext;
    static JTable tblCalendar;
    static JComboBox cmbYear;
    static JFrame frmMain;
    static Container pane;
    static DefaultTableModel mtblCalendar; //Table model
    static JScrollPane stblCalendar; //The scrollpane
    static JPanel pnlCalendar;
    static int realYear, realMonth, realDay, currentYear, currentMonth;
public static void main (String args[]){
    //Look and feel
    try {UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());}
    catch (ClassNotFoundException e) {}
    catch (InstantiationException e) {}
    catch (IllegalAccessException e) {}
    catch (UnsupportedLookAndFeelException e) {}

    //Prepare frame
    frmMain = new JFrame ("Monthly Calendar"); //Create frame
    frmMain.setSize(330, 375); //Set size to 400x400 pixels
    pane = frmMain.getContentPane(); //Get content pane
    pane.setLayout(null); //Apply null layout
    frmMain.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Close when X is clicked

    //Create controls
    lblMonth = new JLabel ("January");
    lblYear = new JLabel ("Change year:");
    cmbYear = new JComboBox();
    btnPrev = new JButton ("<<");
    btnNext = new JButton (">>");
    mtblCalendar = new DefaultTableModel(){public boolean isCellEditable(int rowIndex, int mColIndex){return true;}};
    tblCalendar = new JTable(mtblCalendar);
    stblCalendar = new JScrollPane(tblCalendar);
    pnlCalendar = new JPanel(null);

    //Set border
    pnlCalendar.setBorder(BorderFactory.createTitledBorder("Calendar"));

    //Register action listeners
    btnPrev.addActionListener(new btnPrev_Action());
    btnNext.addActionListener(new btnNext_Action());
    cmbYear.addActionListener(new cmbYear_Action());

    //Add controls to pane
    pane.add(pnlCalendar);
    pnlCalendar.add(lblMonth);
    pnlCalendar.add(lblYear);
    pnlCalendar.add(cmbYear);
    pnlCalendar.add(btnPrev);
    pnlCalendar.add(btnNext);
    pnlCalendar.add(stblCalendar);

    //Set bounds
    pnlCalendar.setBounds(0, 0, 320, 335);
    lblMonth.setBounds(160-lblMonth.getPreferredSize().width/2, 25, 100, 25);
    lblYear.setBounds(10, 305, 80, 20);
    cmbYear.setBounds(230, 305, 80, 20);
    btnPrev.setBounds(10, 25, 50, 25);
    btnNext.setBounds(260, 25, 50, 25);
    stblCalendar.setBounds(10, 50, 300, 250);

    //Make frame visible
    frmMain.setResizable(true);
    frmMain.setVisible(true);

    //Get real month/year
    GregorianCalendar cal = new GregorianCalendar(); //Create calendar
    realDay = cal.get(GregorianCalendar.DAY_OF_MONTH); //Get day
    realMonth = cal.get(GregorianCalendar.MONTH); //Get month
    realYear = cal.get(GregorianCalendar.YEAR); //Get year
    currentMonth = realMonth; //Match month and year
    currentYear = realYear;

    //Add headers
    String[] headers = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"}; //All headers
    for (int i=0; i<7; i++){
        mtblCalendar.addColumn(headers[i]);
    }

    tblCalendar.getParent().setBackground(tblCalendar.getBackground()); //Set background

    //No resize/reorder
    tblCalendar.getTableHeader().setResizingAllowed(true);
    tblCalendar.getTableHeader().setReorderingAllowed(true);

    //Single cell selection
    tblCalendar.setColumnSelectionAllowed(true);
    tblCalendar.setRowSelectionAllowed(true);
    tblCalendar.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

    //Set row/column count
    tblCalendar.setRowHeight(38);
    mtblCalendar.setColumnCount(7);
    mtblCalendar.setRowCount(6);

    //Populate table
    for (int i=realYear-100; i<=realYear+100; i++){
        cmbYear.addItem(String.valueOf(i));
    }


    //Refresh calendar
    refreshCalendar (realMonth, realYear); //Refresh calendar
}

public static void refreshCalendar(int month, int year){
    //Variables
    String[] months =  {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    int nod, som; //Number Of Days, Start Of Month

    //Allow/disallow buttons
    btnPrev.setEnabled(true);
    btnNext.setEnabled(true);
    if (month == 0 && year <= realYear-10){btnPrev.setEnabled(false);} //Too early
    if (month == 11 && year >= realYear+100){btnNext.setEnabled(false);} //Too late
    lblMonth.setText(months[month]); //Refresh the month label (at the top)
    lblMonth.setBounds(160-lblMonth.getPreferredSize().width/2, 25, 180, 25); //Re-align label with calendar
    cmbYear.setSelectedItem(String.valueOf(year)); //Select the correct year in the combo box

    //Clear table
    for (int i=0; i<6; i++){
        for (int j=0; j<7; j++){
            mtblCalendar.setValueAt(null, i, j);
        }
    }

    //Get first day of month and number of days
    GregorianCalendar cal = new GregorianCalendar(year, month, 1);
    nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
    som = cal.get(GregorianCalendar.DAY_OF_WEEK);

    //Draw calendar
    for (int i=1; i<=nod; i++){
        int row = new Integer((i+som-2)/7);
        int column  =  (i+som-2)%7;
        mtblCalendar.setValueAt(i, row, column);
    }

我试图将某些值设置为String而不是int。不幸如果我尝试将setValueAt设置为String，我会收到大量错误。例如 mtblCalendar.setValueAt（＆＃34;工作日＆＃34;，4,3）;会给我很多错误。我得到的一些错误是NumberFormat Exception和其他绘制异常。

    //Apply renderers
    tblCalendar.setDefaultRenderer(tblCalendar.getColumnClass(0), new tblCalendarRenderer());
}

static class tblCalendarRenderer extends DefaultTableCellRenderer{
    public Component getTableCellRendererComponent (JTable table, Object value, boolean selected, boolean focused, int row, int column){
        super.getTableCellRendererComponent(table, value, selected, focused, row, column);
        if (column == 0 || column == 6){ //Week-end
            setBackground(new Color(255, 220, 220));
        }
        else{ //Week
            setBackground(new Color(255, 255, 255));
        }
        if (value != null){
            if (Integer.parseInt(value.toString()) == realDay && currentMonth == realMonth && currentYear == realYear){ //Today
                setBackground(new Color(220, 220, 255));
            }
        }
        setBorder(null);
        setForeground(Color.black);
        return this;  
    }
}

static class btnPrev_Action implements ActionListener{
    public void actionPerformed (ActionEvent e){
        if (currentMonth == 0){ //Back one year
            currentMonth = 11;
            currentYear -= 1;
        }
        else{ //Back one month
            currentMonth -= 1;
        }
        refreshCalendar(currentMonth, currentYear);
    }
}
static class btnNext_Action implements ActionListener{
    public void actionPerformed (ActionEvent e){
        if (currentMonth == 11){ //Foward one year
            currentMonth = 0;
            currentYear += 1;
        }
        else{ //Foward one month
            currentMonth += 1;
        }
        refreshCalendar(currentMonth, currentYear);
    }
}
static class cmbYear_Action implements ActionListener{
    public void actionPerformed (ActionEvent e){
        if (cmbYear.getSelectedItem() != null){
            String b = cmbYear.getSelectedItem().toString();
            currentYear = Integer.parseInt(b);
            refreshCalendar(currentMonth, currentYear);
        }
    }
}

Answer 1

错误是由单元格渲染器tblCalendarRenderer引起的，具体来说是由以下代码引起的：

if (Integer.parseInt(value.toString()) == realDay && currentMonth == realMonth && currentYear == realYear){ //Today
    setBackground(new Color(220, 220, 255));
}

要解决问题，您可以在条件中添加显式类型检查和类型转换：

if (value instanceof Integer && (Integer) value == realDay && ...

Java将表格单元格的值设置为字符串

1 个答案: